Car power source apparatus

Abstract

The car power source apparatus switches a pair of contactors (driving battery relays) connected to positive and negative output sides of a driving battery via a switching circuit with an auxiliary battery as power supply. The switching circuit is provided with a voltage detection circuit to detect auxiliary battery voltage, a series switching circuit to connect coils of the pair of contactors in series and switch both contactor contacts on, and a parallel switching circuit to connect coils of the pair of contactors in parallel and switch both contactor contacts on. When auxiliary battery voltage is higher than a set voltage, it connects the pair of contactor coils in series to switch the contacts on via the series switching circuit, and when auxiliary battery voltage is lower than a set voltage, it connects the pair of contactor coils in parallel to switch the contacts on via the parallel switching circuit.

1. A car power source apparatus comprising a driving battery ( 1 ) having a plurality of batteries connected in series, a pair of contactors ( 2 ) to connect contacts to the positive and negative output sides of the driving battery ( 1 ), a switching circuit ( 4 ) to switch the pair of contactors ( 2 ) on and off, and an auxiliary battery ( 6 ) to electrically power contactor ( 2 ) coils and switch contactor ( 2 ) contacts on and off;
 the switching circuit ( 4 ) is provided with a voltage detection circuit ( 7 ) to detect auxiliary battery ( 6 ) voltage, a series switching circuit to connect coils of the pair of contactors ( 2 ) in series and switch both contactor ( 2 ) contacts on, and a parallel switching circuit to connect coils of the pair of contactors ( 2 ) in parallel and switch both contactor ( 2 ) contacts on; wherein 
 the switching circuit ( 4 ), detects auxiliary battery ( 6 ) voltage via the voltage detection circuit ( 7 ), when auxiliary battery ( 6 ) voltage is higher than a set voltage, it connects the pair of contactor ( 2 ) coils in series to switch the contacts on via the series switching circuit, and when auxiliary battery ( 6 ) voltage is lower than a set voltage, it connects the pair of contactor ( 2 ) coils in parallel to switch the contacts on via the parallel switching circuit. 
 
     
     
       2. A car power source apparatus as recited in  claim 1  wherein the switching circuit ( 4 ), comprising a series switching circuit to connect coils of the pair of contactors ( 2 ) in series and switch both contactor ( 2 ) contacts on, and a parallel switching circuit to connect coils of the pair of contactors ( 2 ) in parallel and switch both contactor ( 2 ) contacts on, is provided with switching devices (Q 1 ), (Q 2 ), (Q 3 ), (Q 4 ) that are switched on and off by the voltage detection circuit ( 7 ), and an intermediate switch ( 8 ) that connects contactor ( 2 ) coils in series;
 two switching devices (Q 1 ), (Q 2 ) are connected to both terminals of the coil of a first contactor ( 2   a ) to connect the first contactor ( 2   a ) coil to the auxiliary battery ( 6 ); 
 another two switching devices (Q 3 ), (Q 4 ) are connected to both terminals of the coil of a second contactor ( 2   b ) to connect the second contactor ( 2   b ) coil to the auxiliary battery ( 6 ); 
 an intermediate switch ( 8 ) is connected to the positive side of the first contactor ( 2   a ) coil and the negative side of the second contactor ( 2   b ) coil; 
 the switching circuit ( 4 ), detects auxiliary battery ( 6 ) voltage via the voltage detection circuit ( 7 ), when auxiliary battery ( 6 ) voltage is lower than the set voltage, it turns on all switching devices (Q 1 ), (Q 2 ), (Q 3 ), (Q 4 ) to connect the first contactor ( 2   a ) coil and second contactor ( 2   b ) coil in parallel with the auxiliary battery ( 6 ) via the switching devices (Q 1 ), (Q 2 ), (Q 3 ), (Q 4 ) and switch the contacts on; 
 when auxiliary battery ( 6 ) voltage is higher than the set voltage, the switching circuit ( 4 ) turns on the switching device (Q 1 ) connected to the negative side of the first contactor ( 2   a ) coil and the switching device (Q 4 ) connected to the positive side of the second contactor ( 2   b ) coil, it turns off the other switching devices (Q 2 ), (Q 3 ), and it turns on the intermediate switch ( 8 ) to connect the first contactor ( 2   a ) coil and second contactor ( 2   b ) coil in series with the auxillary battery ( 6 ) via the switching devices (Q 1 ), (Q 4 ) and switch the contacts on. 
 
     
     
       3. A car power source apparatus as recited in  claim 2  wherein the first contactor ( 2   a ) and the second contactor ( 2   b ) are connected to the positive and negative output sides. 
     
     
       4. A car power source apparatus as recited in  claim 2  wherein the intermediate switch ( 8 ) is a diode. 
     
     
       5. A car power source apparatus as recited in  claim 2  wherein the switching devices (Q 1 ), (Q 2 ), (Q 3 ), (Q 4 ) are FETs (field effect transistors). 
     
     
       6. A car power source apparatus as recited in  claim 2  wherein current limiting resistors (R 1 ), (R 2 ) are connected in series with contactor ( 2 ) coils. 
     
     
       7. A car power source apparatus as recited in  claim 6  wherein current limiting resistors (R 1 ), (R 2 ) are connected in a location where current does not flow through the resistors when contactor ( 2 ) coils are connected in series with the auxiliary battery ( 6 ). 
     
     
       8. A car power source apparatus as recited in  claim 7  wherein the current limiting resistor (R 1 ) is connected between the positive side of the first contactor ( 2   a ) coil and the switching device (Q 2 ), and the current limiting resistor (R 2 ) is connected between the negative side of the second contactor ( 2   b ) coil and the switching device (Q 3 ). 
     
     
       9. A car power source apparatus as recited in  claim 6  wherein the electrical resistance of the current limiting resistors (R 1 ), (R 2 ) is 0 Ω to 10 Ω. 
     
     
       10. A car power source apparatus as recited in  claim 1  wherein a pre-charge circuit ( 3 ) is provided to reduce charging current when contactors ( 2 ) are turned on. 
     
     
       11. A car power source apparatus as recited in  claim 10  wherein the pre-charge circuit ( 3 ) is provided with a precharge relay ( 3 A), which is switched on before the contactors ( 2 );
 the series connection of the pre-charge relay ( 3 A) coil and a pre-charge switching device (Q 5 ) is in turn connected in parallel with the series connection of the coil of the negative side contactor ( 2 B), which connects its contacts with the negative side output terminal, and the switching device (Q 3 ), and the pre-charge relay ( 3 A) is switched on to perform pre-charge with the negative side contactor ( 2 B) switched to the on state.